5,700 research outputs found
Atoms, Radiation, and Radiation Protection
Get PDFAtoms, Radiation, and Radiation Protection offers professionals and advanced students a comprehensive coverage of the major concepts that underlie the origins and transport of ionizing radiation in matter. Understanding atomic structure and the physical mechanisms of radiation interactions is the foundation on which much of the current practice of radiological health protection is based. The work covers the detection and measurement of radiation and the statistical interpretation of the data. The procedures that are used to protect man and the environment from the potential harmful effects o
A metabolic study of the isolated perfused snake liver
Get PDFA metabolic study was made on the isolated, perfused liver of Natrix fasciata fasciata (Linnaeus, 1776). Uric acid production, perfusate protein levels, serum protein patterns, perfusate glucose levels, and bile production were evaluated in this study as criteria of liver function.
The perfused liver was found to produce uric acid up through the fourth hour of perfusion. No significant differences (between the perfusions) were found in uric acid production/ gm of liver tissue.
Perfusate protein and glucose levels were found to be of a fluctuating or cyclic nature. There was found to be an inverse relationship between these two levels: that is, a rise in the protein level was accompanied by a characteristic decrease in the glucose level, the reverse also holding true. Also, both levels were found to be inversely related to liver weight.
Plasma protein pattern studies showed that definite changes were produced within certain specific bands which corresponded to the fluctuations found in the total protein levels. The chemical nature of these bands was also determined.
Bile production was recorded in onzy two. of the five perfusions cecause of the difficulty encountered in cannulating the minute bile duct.
Histological studies revealed some necrosis of the perfused liver tissue.
It was concluded that the isolated liver of N. fasciata fasciata could be perfused in this system from 4 to 5 hours without significant decreases in the functional activities that were examined
A Canadian Perspective
Get PDFThis is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.Advocates the need to continue innovative efforts to provide convenient access to credible information about known existing clinical trials
The Advanced Reusable Technologies Project
Get PDFCurrently, NASA and its industry partners are performing ground testing of hydrogen-fueled rocket based combined-cycle flowpaths. Successful ramjet and scramjet testing at Mach 6 and scramjet testing at Mach 8 have been performed. Cold flow mixing tests have also been successfully performed as have inlet operability tests. Additional testing of RBCC flowpaths at air augmented rocket and rocket only modes is underway
NuSTAR hard X-ray data and Gemini 3D spectra reveal powerful AGN and outflow histories in two low-redshift Lyman- blobs
Full text linkWe have shown that Lyman- blobs (LABs) may still exist even at
, about 7 billion years later than most other LABs known (Schirmer et
al. 2016). Their luminous Ly and [OIII] emitters at offer
new insights into the ionization mechanism. This paper focuses on the two X-ray
brightest LABs at , SDSS J01130106 (J0113) and SDSS J11550147
(J1155), comparable in size and luminosity to `B1', one of the best-studied
LABs at 2. Our NuSTAR hard X-ray (3--30 keV) observations reveal
powerful active galactic nuclei (AGN) with -- erg cm s. J0113 also faded by a
factor of between 2014 and 2016, emphasizing that variable AGN may
cause apparent ionization deficits in LABs. Joint spectral analyses including
Chandra data constrain column densities of cm (J0113) and cm (J1155). J0113 is likely buried in
a torus with a narrow ionization cone, but ionizing radiation is also leaking
in other directions as revealed by our Gemini/GMOS 3D spectroscopy. The latter
shows a bipolar outflow over kpc, with a peculiar velocity profile that is
best explained by AGN flickering. X-ray analysis of J1155 reveals a weakly
absorbed AGN that may ionize over a wide solid angle, consistent with our 3D
spectra. Extinction corrected [OIII] log-luminosities are high, . The
velocity dispersions are low, -- km s, even at the AGN
positions. We argue that this is a combination of high extinction hiding the
turbulent gas, and previous outflows that have cleared the escape paths for
their successors.Comment: 15 pages, 17 Figures, accepted for publication in Ap
Valuing Avoided Soil Erosion by Considering Private and Public Net Benefits
Get PDFThe population in New Zealand is expected to increase to over five million by the mid 2020’s from the current level of 4.3 million (Statistics New Zealand, 2009). An increasing demand for primary produce as a result may put pressure on marginal land to be farmed. Understanding the economic value of avoided erosion in New Zealand is therefore an important factor in policy making to optimise the soil related activities in the economy. Establishing a methodology for estimating the economic value of avoided soil erosion is the first step in assessing the problem. This study uses the future forest scenarios developed by Scion to identify potential afforestation areas and thereby compare the current erosion/sedimentation status under current land-use (non woody vegetation) with potential future afforestation. The study aims to quantify the incremental public and private net benefits from the change in scenario. The notion has come under different headings in the literature, such as on-site and off-site erosion effects or sediment and soil erosion effects, all of which recognize the importance of separation of effects to avoid double-counting. The separation into public and private benefits and costs in this case, while avoiding double-counting, will also help identify appropriate policy instruments to avoid soil erosion damage using the private and public net benefit framework (Pannell, 2008).Environmental Economics and Policy, Land Economics/Use,
Dense gas and HII regions in the starburst galaxy NGC 253
Get PDFThe energetic activity in the nuclear barred region of NGC 253 is attributable to a burst of star formation. NGC 253 is in many ways a twin of the prototypical starburst galaxy M82; the strong non-thermal radio continuum, high far-infrared luminosity, and bright molecular emission of the central 1 Kpc parallel the morphology of the M82 starburst. Furthermore, the filamentary low ionization optical emission and extended x ray emission along the minor axis in NGC 253 is similar to a scaled down version of the well developed galactic bipolar wind in M82. The infrared luminosity of NGC 253, 3(exp 10) solar luminosity, is comparable to M82 but is emitted from a smaller region (Telesco and Harper 1980). This suggests that the NGC 253 starburst may be more intense and at an earlier evolutionary stage than M82. However, the presence of a non-stellar AGN in NGC 253 may complicate the comparison (Turner and Ho, 1985). Researchers used the Hat Creek millimeter interferometer to map emission from the J = 1 to 0 transitions of HCN and HCO(+) as well as 3 mm continuum emission, toward the nuclear region of NGC 253. The HCO(+) and continuum observations are sensitive to spatial scales from 6 to 45 seconds. The 2 minute field of view comfortably includes the entire starburst region (about 40 seconds; 650 pc). Because the longer baseline HCN observations are not yet complete, they are only sensitive to spatial scales from 15 to 45 seconds
Through a Lens Darkly: Evidence for Dusty Gravitational Lenses
Get PDFForeground galaxies that amplify the light from background quasars may also
dim that light if the galaxies contain enough dust. Extinction by dust in
lenses could hide the large number of lensed systems predicted for a flat
universe with a large value of the cosmological constant . We look for
one signature of dust, namely reddening, by examining optical-infrared colors
of gravitationally lensed images of quasars. We find that the lensed systems
identified in radio and infrared searches have redder optical-IR colors than
optically selected ones. This could be due to a bias against selecting reddened
(hence extincted) quasars in the optical surveys, or due to the differences in
the intrinsic colors of optical and radio quasars. Comparison of the
radio-selected lensed and unlensed quasars shows that the lensed ones have
redder colors. We therefore conclude that at least part of the color difference
between the two lens samples is due to dust.
From the color difference between lensed and unlensed radio quasars (and
assuming Galactic extinction law) we can reconcile a large cosmological
constant () with the number of lensed systems observed in flux
limited optical surveys. These results substantially weaken the strongest
constraint on cosmological scenarios that invoke a non-zero cosmological
constant to explain age discrepancy problems, satisfy predictions of
inflationary models of the early universe and play a role in large scale
structure formation models. They also raise the prospect of using gravitational
lenses to study the interstellar medium in high redshift galaxies.Comment: Sumitted to MNRAS, 6 pages, 3 figures. Also available at
http://www.astro.princeton.edu/~san/Abstracts/dusty.htm
- …
